1. Field
This disclosure relates generally to integrated circuits, and more particularly, to non-volatile dynamic random access memories (NVDRAMs).
2. Related Art
Non-volatile memories (NVMs) have become very important in a variety of applications but NVMs typically are slower than other types of memories. Thus it is common to have both NVMs and random access memories (RAMs) on the same integrated circuit because normal operations typically do not require the non-volatile feature. One approach is to combine the non-volatile feature with RAM characteristics. For example, the non-volatile feature is used rarely, such as at power-up and power-down, and the RAM characteristic is used otherwise. The RAM characteristic can be for both interfacing with non-volatile feature for simply a portion of the general purpose RAM. Often the RAM is a static RAM (SRAM), but it can be beneficial for the RAM to be a dynamic RAM (DRAM) due to the smaller size. If general purpose DRAM is going to be present on the integrated circuit anyway, then the use of DRAM cells in combination with NVM cells may be more efficient due to the smaller size than using SRAMs in combination with the NVM cells. Arranging a memory that has both the DRAM characteristic and the NVM characteristic in a manner that is effective in reliably achieving the desired operating characteristics without requiring excessive space has been found to be challenging.
Accordingly there is a need to provide further improvement in obtaining NVDRAMs.